The Washington Post has a record of every recorded vote by every federal Senator and Representative going back to 1991. There's some interesting current-session breakdowns. Of the top ten Senate missed voters, six were at least presidential primary candidates, and two have suffered serious brain illnesses (Kennedy and Johnson). The eight Senate perfect voters have two sets of state delegations--Russ Feingold and Herb Kohl in Wisconsin and Susan Collins and Olympia Snowe in Maine. The individual official's page has breakdowns of key votes, votes missed, and votes against party.